With the rapid development of mobile communications technologies, mobile communications systems of various modes have come into being, for example, a global system of mobile communication (GSM) network, a general packet radio service (GPRS) network, a wideband code division multiple access (WCDMA) network, a CDMA2000 network, a time division-synchronous code division multiple access (TD-SCDMA) network, a worldwide interoperability for microwave access (WiMAX) network, and long term evolution (LTE) network. Such mobile communications systems not only provide voice communication services, but generally also provide data communication services. Therefore, users may upload and download various data by using the data communication services provided by such mobile communications systems.
However, all current communication means are used for sending or receiving data for a single user equipment (UE). Even if another enhanced communication means is used to improve reliability and/or throughput of data transmission of the user equipment, for example, in an LTE system, coordinated multipoint transmission/reception technology (CoMP) is used to improve the reliability of a user equipment at an edge of a cell, and carrier aggregation (CA) is used to improve the throughput of the cell, which is still an operation for a single user equipment. Once the channel condition of the user equipment deteriorates, the throughput and/or reliability of data transmission of the user equipment will drop abruptly.
This requires introduction of multi-user cooperated communication, i.e., data transmission between a base station and a first UE further requires forwarding through a second UE, which makes it possible to select an air interface path, thereby implementing multi-user diversity.
The prior art does not provide a solution how to transmit a media access control packet data unit (MAC PDU) of multi-user cooperated communication.